545t nite lite system in 07 nissan murano

It will only dim if you turn the switch on (on the input side of the BCM).  If you simply power the parking light wires the BCM will have no idea what you are doing so the lights won't dim.

With the electronics in the Murano this might be a fairly difficult task.  The parking light switch is on a data bus.  You can try using a relay to connect the two pins together at the BCM that service the parking light switch but I have personally never had any luck doing this.  The input is multiplexed and in my experiance shorting the two wires out causes all the functions on that branch of the bus to turn on.